Multilayer ceramic capacitor

ABSTRACT

A multilayer ceramic capacitor includes a multilayer body, a first internal electrode layer extending to opposing end surfaces of the multilayer body, a second internal electrode layer extending to opposing side surfaces of the multilayer body, first and second external electrodes connected to the first internal electrode layer and provided on the opposing end surfaces, and third and fourth external electrodes connected to the second internal electrode layer and provided on the opposing side surfaces. The second internal electrode layer includes a central section in a central portion of the dielectric layer and an extending section extending to the opposing side surfaces. The first internal electrode layer is larger in number than the second internal electrode layer, at least two first internal electrode layers are successively layered, and the extending section is larger in thickness than the central section located in the central portion of the dielectric layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2020-145004 filed on Aug. 28, 2020. The entire contentsof this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a multilayer ceramic capacitor.

2. Description of the Related Art

A multilayer through-type capacitor with a general structure asdescribed in Japanese Patent Laid-Open No. 2000-58376 has been known,for example, as an antinoise component of a decoupling capacitor usedfor stabilizing a power supply voltage supplied to an integrated circuit(IC) component that operates at a high speed or a line for power supplyto an integrated circuit (IC) component. The through-type capacitordescribed in Japanese Patent Laid-Open No. 2000-58376 includes a generalstructure, and includes a ceramic element (multilayer body) including anouter surface including first and second main surfaces opposed to eachother, first and second side surfaces opposed to each other, and firstand second end surfaces opposed to each other. In the inside of theceramic element, a plurality of first internal electrodes and aplurality of second internal electrodes are alternately provided in adirection of layering. The first internal electrode has opposing endsdrawn to the first and second end surfaces, and the second internalelectrode has opposing ends drawn to the first and second side surfaces.

In such a multilayer through-type capacitor, for lowering a capacitance,the number of internal electrodes should be reduced and hence a value ofa direct-current (DC) resistance (Rdc) of the internal electrode becomeslarge. Accordingly, an amount of heat generation in the multilayerthrough-type capacitor may be large.

As in Japanese Patent Laid-Open No. 9-55335, a structure in which aplurality of through electrodes are successively layered has been knownas a structure that can achieve suppression of increase in DC resistancewhile increase in capacitance is suppressed. Since a value of the DCresistance (Rdc) can also be made smaller while the capacitance islowered according to the structure described in Japanese PatentLaid-Open No. 9-55335, the amount of heat generation can also besuppressed.

In an attempt to further lower a capacitance in the structure as inJapanese Patent Laid-Open No. 9-55335, however, ground electrodes drawnto opposing side surfaces of the multilayer body should be reduced. Inthat case, since portions of connection between the ground electrodesand the external electrodes are reduced, connectivity therebetween maynot sufficiently be secured.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide multilayerceramic capacitors that are each able to significantly reduce or preventan increase in DC resistance while providing a lower capacitance andfurther able to secure connectivity between an internal electrode layerand an external electrode.

A multilayer ceramic capacitor according to a preferred embodiment ofthe present invention includes a multilayer body including a pluralityof layered dielectric layers, the multilayer body including a first mainsurface and a second main surface opposed to each other in a heightdirection, a first end surface and a second end surface opposed to eachother in a length direction orthogonal or substantially orthogonal tothe height direction, and a first side surface and a second side surfaceopposed to each other in a width direction orthogonal or substantiallyorthogonal to the height direction and the length direction, a pluralityof first internal electrode layers on the plurality of dielectric layersand extending to the first end surface and the second end surface, aplurality of second internal electrode layers on the plurality ofdielectric layers and extending to the first side surface and the secondside surface, a first external electrode on the first end surface andconnected to the first internal electrode layers, a second externalelectrode on the second end surface and connected to the first internalelectrode layers, a third external electrode on the first side surfaceand connected to the second internal electrode layers, and a fourthexternal electrode on the second side surface and connected to thesecond internal electrode layers. Each of the second internal electrodelayers includes a central section located in a central portion of thedielectric layer and an extending section that extends from the centralsection located in the central portion of the dielectric layer to thefirst side surface and the second side surface. The first internalelectrode layers are larger in number than the second internal electrodelayers, at least two of the first internal electrode layers aresuccessively layered, and the extending section is larger in thicknessthan the central section located in the central portion of thedielectric layer.

The above and other elements, features, steps, characteristics, andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external perspective view showing a multilayer ceramiccapacitor (three-terminal multilayer ceramic capacitor) according to apreferred embodiment of the present invention.

FIG. 2 is a top view showing a multilayer ceramic capacitor(three-terminal multilayer ceramic capacitor) according to a preferredembodiment of the present invention.

FIG. 3 is a side view showing a multilayer ceramic capacitor(three-terminal multilayer ceramic capacitor) according to a preferredembodiment of the present invention.

FIG. 4 is a cross-sectional view along the line IV-IV in FIG. 1 .

FIG. 5 is a cross-sectional view along the line V-V in FIG. 1 .

FIG. 6 is a cross-sectional view along the line VI-VI in FIG. 4 .

FIG. 7 is a cross-sectional view along the line VII-VII in FIG. 4 .

FIG. 8 shows a modification of a second internal electrode layer shownin FIG. 7 .

FIG. 9 is a cross-sectional view showing a multilayer ceramic capacitor(Comparative Example 1-3) according to Comparative Example 1.

FIG. 10 is a cross-sectional view showing a multilayer ceramic capacitor(Comparative Example 2-3) according to Comparative Example 2.

FIG. 11 is a diagram showing heat generation characteristics withvariation in value of a current between external electrodes inmultilayer ceramic capacitors in Example, Comparative Example 1, andComparative Example 2.

FIG. 12 is a diagram showing a value of a DC resistance depending on adifference in capacitance in multilayer ceramic capacitors in Example ofa preferred embodiment of the present invention and Comparative Example1.

FIG. 13 is a diagram showing relation between the number of layeredsecond internal electrodes and a ratio of defective connection inmultilayer ceramic capacitors in Example and Comparative Example 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 1. Multilayer CeramicCapacitor

A multilayer ceramic capacitor according to a preferred embodiment ofthis invention will be described. The multilayer ceramic capacitoraccording to the present preferred embodiment is a three-terminalmultilayer ceramic capacitor.

FIG. 1 is an external perspective view showing a multilayer ceramiccapacitor (three-terminal multilayer ceramic capacitor) according to apreferred embodiment of this invention. FIG. 2 is a top view showing amultilayer ceramic capacitor (three-terminal multilayer ceramiccapacitor) according to a preferred embodiment of this invention. FIG. 3is a side view showing a multilayer ceramic capacitor (three-terminalmultilayer ceramic capacitor) according to a preferred embodiment ofthis invention. FIG. 4 is a cross-sectional view along the line IV-IV inFIG. 1 . FIG. 5 is a cross-sectional view along the line V-V in FIG. 1 .FIG. 6 is a cross-sectional view along the line VI-VI in FIG. 4 . FIG. 7is a cross-sectional view along the line VII-VII in FIG. 4 . FIG. 8shows a modification of a second internal electrode layer shown in FIG.7 .

As shown in FIGS. 1 to 3 , a multilayer ceramic capacitor 10 includes amultilayer body 12 in a shape, for example, of a parallelepiped and anexternal electrode 30.

Multilayer body 12 includes a plurality of layered dielectric layers 14and a plurality of internal electrode layers 16 layered on dielectriclayer 14. Multilayer body 12 includes a first main surface 12 a and asecond main surface 12 b opposed to each other in a height direction x,a first side surface 12 c and a second side surface 12 d opposed to eachother in a width direction y orthogonal or substantially orthogonal toheight direction x, and a first end surface 12 e and a second endsurface 12 f opposed to each other in a length direction z orthogonal orsubstantially orthogonal to height direction x and width direction y.Multilayer body 12 includes a corner and a ridgeline that are rounded.The corner refers to a portion where three adjacent surfaces of themultilayer body meet one another and the ridgeline refers to a portionwhere two adjacent surfaces of the multilayer body meet each other.Projections and recesses or the like may be provided in a portion or anentirety of first main surface 12 a and second main surface 12 b, firstside surface 12 c and second side surface 12 d, and first end surface 12e and second end surface 12 f.

A dimension of multilayer body 12 is not particularly limited.

Multilayer body 12 includes an inner layer portion 18 and a firstmain-surface-side outer layer portion 20 a and a secondmain-surface-side outer layer portion 20 b that sandwich inner layerportion 18 in height direction x.

Inner layer portion 18 includes a plurality of dielectric layers 14 anda plurality of internal electrode layers 16. Inner layer portion 18includes internal electrode layers from internal electrode layer 16located closest to first main surface 12 a in height direction x tointernal electrode layer 16 located closest to second main surface 12 b.In inner layer portion 18, the plurality of internal electrode layers 16are opposed to each other with dielectric layer 14 being interposedtherebetween. Inner layer portion 18 is a portion that produces acapacitance and substantially defines and functions as a capacitor.

First main-surface-side outer layer portion 20 a is located on a side offirst main surface 12 a. First main-surface-side outer layer portion 20a is an assembly including a plurality of dielectric layers 14 locatedbetween first main surface 12 a and internal electrode layer 16 closestto first main surface 12 a.

Second main-surface-side outer layer portion 20 b is located on a sideof second main surface 12 b. Second main-surface-side outer layerportion 20 b is an assembly including a plurality of dielectric layers14 located between second main surface 12 b and internal electrode layer16 closest to second main surface 12 b. Dielectric layers 14 included ineach of first main-surface-side outer layer portion 20 a and secondmain-surface-side outer layer portion 20 b may be the same orsubstantially the same as dielectric layers 14 included in inner layerportion 18.

Multilayer body 12 includes a first side-surface-side outer layerportion 22 a located on a side of first side surface 12 c and includinga plurality of dielectric layers 14 located between first side surface12 c and an outermost surface of inner layer portion 18 on the side offirst side surface 12 c.

Similarly, multilayer body 12 includes a second side-surface-side outerlayer portion 22 b located on a side of second side surface 12 d andincluding a plurality of dielectric layers 14 located between secondside surface 12 d and an outermost surface of inner layer portion 18 onthe side of second side surface 12 d.

FIG. 5 shows a range in width direction y of each of firstside-surface-side outer layer portion 22 a and second side-surface-sideouter layer portion 22 b. Magnitude of a width in width direction y ofeach of first side-surface-side outer layer portion 22 a and secondside-surface-side outer layer portion 22 b is also referred to as a Wgap or a side gap.

Multilayer body 12 includes a first end-surface-side outer layer portion24 a located on a side of first end surface 12 e and including aplurality of dielectric layers 14 located between first end surface 12 eand an outermost surface of inner layer portion 18 on the side of firstend surface 12 e.

Similarly, multilayer body 12 includes a second end-surface-side outerlayer portion 24 b located on a side of second end surface 12 f andincluding a plurality of dielectric layers 14 located between second endsurface 12 f and an outermost surface of inner layer portion 18 on theside of second end surface 12 f.

FIG. 4 shows a range in length direction z of each of firstend-surface-side outer layer portion 24 a and second end-surface-sideouter layer portion 24 b. Magnitude of a width in length direction z ofeach of first end-surface-side outer layer portion 24 a and secondend-surface-side outer layer portion 24 b is also referred to as an Lgap or an end gap.

Dielectric layer 14 may be defined by, for example, a dielectricmaterial as a ceramic material. For example, dielectric ceramicsincluding a component such as BaTiO₃, CaTiO₃, SrTiO₃, or CaZrO₃ may beincluded as a dielectric material. When the aforementioned dielectricmaterial is included as a main component, depending on a predeterminedcharacteristic of multilayer body 12, for example, a sub-component lowerin content than the main component, such as, for example, an Mncompound, an Fe compound, a Cr compound, a Co compound, or an Nicompound may be added.

Fired dielectric layer 14 preferably has a thickness not smaller thanabout 0.5 μm and not larger than about 10 μm, for example.

The number of layered dielectric layers 14 is preferably not smallerthan fifteen and not larger than three hundred, for example. The numberof dielectric layers 14 is a total of the number of dielectric layers 14in inner layer portion 18 and the number of dielectric layers 14 infirst main-surface-side outer layer portion 20 a and secondmain-surface-side outer layer portion 20 b.

Multilayer body 12 includes a plurality of first internal electrodelayers 16 a and a plurality of second internal electrode layers 16 b asthe plurality of internal electrode layers 16.

First internal electrode layer 16 a is provided on dielectric layer 14.

As shown in FIG. 6 , first internal electrode layer 16 a includes afirst section 26 a that extends between first end surface 12 e andsecond end surface 12 f of multilayer body 12 and corresponds to acentral portion thereof, a second section 26 b that extends from firstsection 26 a to first end surface 12 e of multilayer body 12 e, and athird section 26 c that extends from first section 26 a to second endsurface 12 f of multilayer body 12. First section 26 a is located in thecentral portion on dielectric layer 14. Second section 26 b is exposedat first end surface 12 e of multilayer body 12 and third section 26 cis exposed at second end surface 12 f of multilayer body 12. Therefore,first internal electrode layer 16 a is not exposed at first side surface12 c and second side surface 12 d of multilayer body 12.

Although a shape of first internal electrode layer 16 a is notparticularly limited, first internal electrode layer 16 a is preferablyrectangular or substantially rectangular and a corner thereof may berounded, for example.

Second internal electrode layer 16 b is provided on dielectric layer 14different from dielectric layer 14 on which first internal electrodelayer 16 a is provided.

As shown in FIG. 7 , second internal electrode layer 16 b includes afourth section 28 a that extends between first side surface 12 c andsecond side surface 12 d of multilayer body 12 and corresponds to acentral portion thereof, a fifth section 28 b that extends from fourthsection 28 a to first side surface 12 c, and a sixth section 28 c thatextends from fourth section 28 a to second side surface 12 d. Fourthsection 28 a has a rectangular or substantially rectangular shapeextending toward first end surface 12 e and extending toward second endsurface 12 f. Fourth section 28 a is located in the central portion ondielectric layer 14. Fifth section 28 b is exposed at first side surface12 c of multilayer body 12 and sixth section 28 c is exposed at secondside surface 12 d of multilayer body 12. Therefore, second internalelectrode layer 16 b is not exposed at first end surface 12 e and secondend surface 12 f of multilayer body 12.

Although a shape of fourth section 28 a and a shape of each of fifthsection 28 b and sixth section 28 c of second internal electrode layer16 b are not particularly limited, the sections are preferablyrectangular or substantially rectangular, for example. The corner ofeach section may be rounded.

First section 26 a of first internal electrode layer 16 a is opposed tofourth section 28 a of second internal electrode layer 16 b.

A width of first section 26 a of first internal electrode layer 16 a inwidth direction y that connects between first side surface 12 c andsecond side surface 12 d may be equal to or different from a width offourth section 28 a of second internal electrode layer 16 b in widthdirection y that connects between first side surface 12 c and secondside surface 12 d.

Relationship of A B is preferably satisfied, where A represents a widthof fourth section 28 a of second internal electrode layer 16 b in lengthdirection z that connects between first end surface 12 e and second endsurface 12 f and B represents a width of fifth section 28 b and sixthsection 28 c of second internal electrode layer 16 b in length directionz that connects between first end surface 12 e and second end surface 12f.

For example, as shown in FIG. 8 , in a modification of second internalelectrode layer 16 b, fourth section 28 a of second internal electrodelayer 16 b may not extend toward first end surface 12 e and second endsurface 12 f and width A of fourth section 28 a of second internalelectrode layer 16 b in length direction z that connects between firstend surface 12 e and second end surface 12 f may be equal orsubstantially equal to width B of each of fifth section 28 b and sixthsection 28 c of second internal electrode layer 16 b in length directionz that connects between first end surface 12 e and second end surface 12f.

Thus, by adjusting only an area of second internal electrode layer 16 bwithout changing an area of first internal electrode layer 16 a, acapacitance of multilayer ceramic capacitor 10 is able to be loweredwith a DC resistance remaining low.

Although not shown, relationship of A<B may be satisfied.

First internal electrode layers 16 a are larger in number than secondinternal electrode layers 16 b, and at least two first internalelectrode layers 16 a are successively layered. Thus, multilayer ceramiccapacitor 10 shown in FIG. 1 is not only larger in number of firstinternal electrode layers 16 a and larger in number of first internalelectrode layers 16 a connected in parallel while increase incapacitance is significantly reduced or prevented, but alsosignificantly improved in conduction between first internal electrodelayers 16 a and external electrode 30, and thus multilayer ceramiccapacitor 10 significantly reduces or prevents an increase in DCresistance. Fifth section 28 b and sixth section 28 c of second internalelectrode layer 16 b are larger in thickness than fourth section 28 a ofsecond internal electrode layer 16 b. Thus, even when the capacitance islowered, connectivity between second internal electrode layers 16 b andexternal electrode 30 is also able to be secured.

Though the number of first internal electrode layers 16 a is notparticularly limited, for example, it is preferably not smaller thanthirty and not larger than one hundred.

The number of second internal electrode layers 16 b is at least smallerthan the number of first internal electrode layers 16 a. Specifically,though the number of second internal electrode layers 16 b is notparticularly limited, for example, it is preferably not smaller than oneand not larger than fifty.

Though a thickness of first internal electrode layer 16 a is notparticularly limited, for example, the thickness is preferably notsmaller than about 0.5 μm and not larger than about 2.0 μm.

Though the thickness of fourth section 28 a of second internal electrodelayer 16 b is not particularly limited, for example, the thickness ispreferably not smaller than about 0.5 μm and not larger than about 2.0μm.

Fifth section 28 b and sixth section 28 c of second internal electrodelayer 16 b are larger in thickness than fourth section 28 a of secondinternal electrode layer 16 b. Specifically, though the thickness offifth section 28 b and sixth section 28 c of second internal electrodelayer 16 b is not particularly limited, for example, the thickness ispreferably not smaller than about 1 μm and not larger than about 3 μm.

The thickness of fourth section 28 a of second internal electrode layer16 b and the thickness of fifth section 28 b and sixth section 28 c ofsecond internal electrode layer 16 b preferably satisfy relationship ofthe thickness of the fifth section and the sixth section of the secondinternal electrode layer/the thickness of the fourth section of thesecond internal electrode layer≥about 1.2. Thus, even when a smallernumber of second internal electrode layers 16 b are layered,connectivity between second internal electrode layers 16 b and externalelectrode 30 is able to be further improved.

Inner layer portion 18 of multilayer body 12 includes a capacitanceforming portion 19 in which first internal electrode layer 16 a andsecond internal electrode layer 16 b are opposed to each other withdielectric layer 14 being interposed therebetween to define acapacitance and an internal electrode layered portion 25 which is aregion where at least two first internal electrode layers 16 a aresuccessively layered. Multilayer ceramic capacitor 10 exhibitscharacteristics of the capacitor due to capacitance forming portion 19.

Internal electrode layered portion 25 is divided into a plurality ofinternal electrode layered portions by second internal electrode layers16 b. Since an assembly of first internal electrode layers 16 a is thusdistributed, a heat radiation effect is able to be improved and areduction or prevention of a temperature increase is able to beprovided.

In multilayer ceramic capacitor 10 shown in FIG. 1 , internal electrodelayered portion 25 is divided by two second internal electrode layers 16b into a first internal electrode layered portion 25 a, a secondinternal electrode layered portion 25 b, and a third internal electrodelayered portion 25 c as shown in FIG. 4 .

A single second internal electrode layer 16 b may divide internalelectrode layered portion 25 which is the region where at least twofirst internal electrode layers 16 a are successively layered. A largernumber of first internal electrode layers 16 a is thus able to belayered and a DC resistance lowering effect is able to be provided.

At least two second internal electrode layers 16 b may be successivelylayered to divide internal electrode layered portion 25 which is theregion where at least two first internal electrode layers 16 a aresuccessively layered. Thus, even when the number of second internalelectrode layers 16 b is smaller, connectivity between second internalelectrode layers 16 b and external electrode 30 is able to be increased.

Second internal electrode layer 16 b may be provided in internalelectrode layered portion 25 which is the region where at least twofirst internal electrode layers 16 a located on the side of first mainsurface 12 a of multilayer body 12 are successively layered, that is,between first internal electrode layered portion 25 a and first mainsurface 12 a, and in internal electrode layered portion 25 which is theregion where at least two first internal electrode layers 16 a locatedon the side of second main surface 12 b of multilayer body 12 aresuccessively layered, that is, between third internal electrode layeredportion 25 c and second main surface 12 b. Since capacitance formingportion 19 is thus able to be provided also around firstmain-surface-side outer layer portion 20 a and second main-surface-sideouter layer portion 20 b, some of the capacitance is provided, a currentpath to a mount substrate is able to be relatively short, and arelatively low ESL effect is able to be provided.

Second internal electrode layer 16 b does not have to be provided ininternal electrode layered portion 25 which is the region where at leasttwo first internal electrode layers 16 a located on the side of firstmain surface 12 a of multilayer body 12 are successively layered, thatis, between first internal electrode layered portion 25 a and first mainsurface 12 a, and in internal electrode layered portion 25 which is theregion where at least two first internal electrode layers 16 a locatedon the side of second main surface 12 b of multilayer body 12 aresuccessively layered, that is, between third internal electrode layeredportion 25 c and second main surface 12 b. A distance from the surfaceof multilayer body 12 to capacitance forming portion 19 where thecapacitance is formed is thus longer. Therefore, even when a crack runsfrom the surface of multilayer body 12 due to external load, an effectof lower tendency toward deterioration of insulation resistance is ableto be provided.

Dielectric layer 14 adjacent to second internal electrode layer 16 b ispreferably larger in thickness than dielectric layer 14 lying betweenfirst internal electrode layers 16 a. A larger number of first internalelectrode layers 16 a is thus able to be layered, and the DC resistancelowering effect is able to further increased.

First internal electrode layer 16 a and second internal electrode layer16 b may be made of an appropriate conductive material including, forexample, a metal such as Ni, Cu, Ag, Pd, or Au and an alloy including atleast one of those metals, such as an Ag—Pd alloy.

External electrode 30 is provided on the side of each of first endsurface 12 e and second end surface 12 f as well as on the side of eachof first side surface 12 c and second side surface 12 d of multilayerbody 12. External electrode 30 includes a first external electrode 30 a,a second external electrode 30 b, a third external electrode 30 c, and afourth external electrode 30 d.

First external electrode 30 a is provided on first end surface 12 e ofmultilayer body 12. First external electrode 30 a extends from first endsurface 12 e of multilayer body 12 to cover a portion of each of firstmain surface 12 a, second main surface 12 b, first side surface 12 c,and second side surface 12 d. First external electrode 30 a iselectrically connected to second section 26 b of first internalelectrode layer 16 a exposed at first end surface 12 e of multilayerbody 12. First external electrode 30 a may be provided only on first endsurface 12 e of multilayer body 12.

Second external electrode 30 b is provided on second end surface 12 f ofmultilayer body 12. Second external electrode 30 b extends from secondend surface 12 f of multilayer body 12 to cover a portion of each offirst main surface 12 a, second main surface 12 b, first side surface 12c, and second side surface 12 d. Second external electrode 30 b iselectrically connected to third section 26 c of first internal electrodelayer 16 a exposed at second end surface 12 f of multilayer body 12.Second external electrode 30 b may be provided only on second endsurface 12 f of multilayer body 12.

Third external electrode 30 c is provided on first side surface 12 c ofmultilayer body 12. Third external electrode 30 c extends from firstside surface 12 c to cover a portion of each of first main surface 12 aand second main surface 12 b. Third external electrode 30 c iselectrically connected to fifth section 28 b of second internalelectrode layer 16 b exposed at first side surface 12 c of multilayerbody 12. Third external electrode 30 c may be provided only on firstside surface 12 c of multilayer body 12.

Fourth external electrode 30 d is provided on second side surface 12 dof multilayer body 12. Fourth external electrode 30 d extends fromsecond side surface 12 d to cover a portion of each of first mainsurface 12 a and second main surface 12 b. Fourth external electrode 30d is electrically connected to sixth section 28 c of second internalelectrode layer 16 b exposed at second side surface 12 d of multilayerbody 12. Fourth external electrode 30 d may be provided only on secondside surface 12 d of multilayer body 12.

Since second internal electrode layer 16 b is larger in thickness thanfirst internal electrode layer 16 a, connectivity between fifth section28 b of second internal electrode layer 16 b and third externalelectrode 30 c provided on first side surface 12 c is able to beprovided and connectivity between sixth section 28 c of second internalelectrode layer 16 b and fourth external electrode 30 d provided onsecond side surface 12 d is able to be provided.

As long as the thickness of first internal electrode layer 16 a and thethickness of second internal electrode layer 16 b satisfy relationshipof the thickness of the second internal electrode layer/the thickness ofthe first internal electrode layer about 1.2, connectivity between fifthsection 28 b of second internal electrode layer 16 b and third externalelectrode 30 c provided on first side surface 12 c is able to beprovided and connectivity between sixth section 28 c of second internalelectrode layer 16 b and fourth external electrode 30 d provided onsecond side surface 12 d is able to be provided even when the number ofsecond internal electrode layers 16 b is relatively low.

External electrode 30 includes an underlying electrode layer 32 providedon the surface of multilayer body 12 and a plated layer 34 coveringunderlying electrode layer 32.

Underlying electrode layer 32 includes a first underlying electrodelayer 32 a, a second underlying electrode layer 32 b, a third underlyingelectrode layer 32 c, and a fourth underlying electrode layer 32 d.

First underlying electrode layer 32 a is provided on the surface offirst end surface 12 e of multilayer body 12 and extends from first endsurface 12 e to cover a portion of each of first main surface 12 a,second main surface 12 b, first side surface 12 c, and second sidesurface 12 d.

Second underlying electrode layer 32 b is provided on the surface ofsecond end surface 12 f of multilayer body 12 and extends from secondend surface 12 f to cover a portion of each of first main surface 12 a,second main surface 12 b, first side surface 12 c, and second sidesurface 12 d.

First underlying electrode layer 32 a may be provided only on thesurface of first end surface 12 e of multilayer body 12 and secondunderlying electrode layer 32 b may be provided only on the surface ofsecond end surface 12 f of multilayer body 12.

Third underlying electrode layer 32 c is provided on the surface offirst side surface 12 c of multilayer body 12 and extends from firstside surface 12 c to cover a portion of each of first main surface 12 aand second main surface 12 b.

Fourth underlying electrode layer 32 d is provided on the surface ofsecond side surface 12 d of multilayer body 12 and extends from secondside surface 12 d to cover a portion of each of first main surface 12 aand second main surface 12 b.

Third underlying electrode layer 32 c may be provided only on thesurface of first side surface 12 c of multilayer body 12 and fourthunderlying electrode layer 32 d may be provided only on the surface ofsecond side surface 12 d of multilayer body 12.

Underlying electrode layer 32 includes at least one selected from abaked layer, a conductive resin layer, a thin layer, and the like.

A construction in which underlying electrode layer 32 is formed from thebaked layer, the conductive resin layer, or the thin layer will bedescribed below.

Baked Layer

The baked layer includes a glass component and a metal component. Theglass component for the baked layer includes, for example, at least oneselected from B, Si, Ba, Mg, Al, Li, and the like. The metal componentfor the baked layer includes at least one selected, for example, fromCu, Ni, Ag, Pd, an Ag—Pd alloy, Au, and the like. The baked layer mayinclude a plurality of layers. The baked layer is provided by applying aconductive paste including a glass component and a metal component tomultilayer body 12 and baking the conductive paste. The baked layer maybe provided by simultaneously firing a multilayer chip includinginternal electrode layers 16 and dielectric layers 14 and the conductivepaste applied to the multilayer chip, or may be provided by firing amultilayer chip including internal electrode layers 16 and dielectriclayers 14 to provide multilayer body 12 and thereafter applying aconductive paste to multilayer body 12 and baking multilayer body 12.When the baked layer is provided by simultaneously firing the multilayerchip including internal electrode layers 16 and dielectric layers 14 andthe conductive paste applied to the multilayer chip, the baked layer ispreferably formed, for example, by baking a material to which adielectric material is added instead of the glass component.

A thickness in the direction of connection between first end surface 12e and second end surface 12 f, of first underlying electrode layer 32 alocated on first end surface 12 e at the central portion in heightdirection x is preferably not smaller than about 3 μm and not largerthan about 70 μm, for example.

A thickness in the direction of connection between first end surface 12e and second end surface 12 f, of second underlying electrode layer 32 blocated on second end surface 12 f at the central portion in heightdirection x is preferably not smaller than about 3 μm and not largerthan about 70 μm, for example.

When underlying electrode layer 32 is provided on a portion of firstmain surface 12 a and a portion of second main surface 12 b as well ason a portion of first side surface 12 c and a portion of second sidesurface 12 d, a thickness of first underlying electrode layer 32 alocated on first main surface 12 a and second main surface 12 b and onfirst side surface 12 c and second side surface 12 d in the heightdirection of connection between first main surface 12 a and second mainsurface 12 b at a central portion in length direction z is preferably,for example, not smaller than about 3 μm and not larger than about 40μm.

When underlying electrode layer 32 is provided on a portion of firstmain surface 12 a and a portion of second main surface 12 b as well ason a portion of first side surface 12 c and a portion of second sidesurface 12 d, a thickness of second underlying electrode layer 32 blocated on first main surface 12 a and second main surface 12 b and onfirst side surface 12 c and second side surface 12 d in the heightdirection of connection between first main surface 12 a and second mainsurface 12 b at a central portion in length direction z is preferably,for example, not smaller than about 3 μm and not larger than about 40μm.

Conductive Resin Layer

The conductive resin layer may include a plurality of layers.

The conductive resin layer may be provided on the baked layer to coverthe bakes layer, or may directly be provided on multilayer body 12.

The conductive resin layer includes a thermosetting resin and a metal.

The conductive resin layer may completely cover underlying electrodelayer 32 or may cover a portion of underlying electrode layer 32.

Since the conductive resin layer includes a thermosetting resin, it ismore flexible than a conductive layer formed, for example, from a platedfilm or a fired product of a conductive paste. Therefore, even though aphysical shock or a shock originating from a thermal cycle is applied tomultilayer ceramic capacitor 10, the conductive resin layer defines andfunctions as a buffer layer and is able to significantly reduce orprevent a crack in multilayer ceramic capacitor 10.

For example, Ag, Cu, Ni, Sn, Bi, or an alloy thereof may be included asa metal to be included in the conductive resin layer.

Alternatively, metal powders with a surface coated with Ag are also ableto be included. In including metal powders having a surface coated withAg, Cu, Ni, Sn, Bi, or powders of an alloy thereof is/are preferablyused for the metal powders, for example. Conductive metal powders of Agare used as a conductive metal because Ag is suitable as an electrodematerial because of its specific resistance lowest among metals and Agwhich is a precious metal is not oxidized and highly weather resistantand because a metal as a base material is relatively inexpensive whilethe characteristics of Ag are maintained.

Cu or Ni subjected to antioxidation treatment can also be used as ametal included in the conductive resin layer.

Metal powders having a surface coated with, for example, Sn, Ni, or Cuare also able to be used as a metal to be included in the conductiveresin layer. In providing metal powders having a surface coated with Sn,Ni, or Cu, Ag, Cu, Ni, Sn, or Bi or powders of an alloy thereof is/arepreferably provided for the metal powders, for example.

The conductive resin layer preferably includes at least about 35 vol %and at most about 75 vol % of metal with respect to a volume of theconductive resin as a whole, for example.

An average particle size of the metal included in the conductive resinlayer is not particularly limited. A conductive filler may have anaverage particle size, for example, not smaller than about 0.3 μm andnot larger than about 10 μm.

The metal included in the conductive resin layer mainly provides forcurrent conduction in the conductive resin layer. Specifically, acurrent conduction path is formed in the conductive resin layer as aresult of contact between the conductive fillers.

Although the metal included in the conductive resin layer may bespherical or may have a flat profile, spherical metal powders and metalpowders having a flat profile are preferably used as being mixed, forexample.

Various known thermosetting resins, for example, an epoxy resin, aphenol resin, a urethane resin, a silicone resin, and a polyimide resinare able to be used as the resin in the conductive resin layer. Amongthese, the epoxy resin excellent in heat resistance, moistureresistance, and adhesiveness is one of most appropriate resins.

The conductive resin layer preferably includes at least about 25 vol %and at most about 65 vol % of resin with respect to the volume of theconductive resin as a whole, for example.

The conductive resin layer preferably includes a hardening agenttogether with the thermosetting resin, for example. When the epoxy resinis provided as a base resin, various known compounds, for example, aphenol-based compound, an amine-based compound, an acid anhydride-basedcompound, an imidazole-based compound, an active-ester-based compound,and an amide-imide-based compound may be included as the hardening agentfor the epoxy resin.

The conductive resin layer located in the central portion in heightdirection x of multilayer body 12 located on each of first end surface12 e and second end surface 12 f has a thickness, for example,preferably not smaller than about 10 μm and not larger than about 150μm.

Thin Layer

When a thin layer is provided as underlying electrode layer 32, the thinlayer is not larger than about 1 μm that is provided by deposition ofmetal particles by a thin film formation method, for example, sputteringor vapor deposition.

Plated layer 34 includes a first plated layer 34 a, a second platedlayer 34 b, a third plated layer 34 c, and a fourth plated layer 34 d.

First plated layer 34 a, second plated layer 34 b, third plated layer 34c, and fourth plated layer 34 d include at least one selected, forexample, from Cu, Ni, Sn, Ag, Pd, an Ag—Pd alloy, Au, and the like.

First plated layer 34 a covers first underlying electrode layer 32 a.

Second plated layer 34 b covers second underlying electrode layer 32 b.

Third plated layer 34 c covers third underlying electrode layer 32 c.

Fourth plated layer 34 d covers fourth underlying electrode layer 32 d.

Plated layer 34 may include a plurality of layers. In this case, platedlayer 34 preferably has a two-layered structure including a lower platedlayer of Ni plating provided on underlying electrode layer 32 and anupper plated layer of Sn plating provided on the lower plated layer, forexample.

Specifically, first plated layer 34 a includes a first lower platedlayer and a first upper plated layer located on a surface of the firstlower plated layer.

Second plated layer 34 b includes a second lower plated layer and asecond upper plated layer located on a surface of the second lowerplated layer.

Third plated layer 34 c includes a third lower plated layer and a thirdupper plated layer located on a surface of the third lower plated layer.

Fourth plated layer 34 d includes a fourth lower plated layer and afourth upper plated layer located on a surface of the fourth lowerplated layer.

The lower plated layer of Ni plating is included to significantly reduceor prevent corrosion of underlying electrode layer 32 by solder thatmounts of multilayer ceramic capacitor 10 and the upper plated layer ofSn plating is included to increase wettability of solder that mounts ofmultilayer ceramic capacitor 10.

One plated layer has a thickness preferably not smaller than about 2.0μm and not larger than about 15.0 μm, for example.

External electrode 30 may be provided only from a plated layer withoutproviding underlying electrode layer 32.

A structure where a plated layer is provided without underlyingelectrode layer 32 will be described below, although it is not shown.

Any one or each of first external electrode 30 a to fourth externalelectrode 30 d may include no underlying electrode layer 32, and mayinclude the plated layer directly provided on the surface of multilayerbody 12. In other words, multilayer ceramic capacitor 10 may bestructured to include a plated layer electrically connected to firstinternal electrode layer 16 a and second internal electrode layer 16 b.In such a case, the plated layer may be formed after a catalyst isprovided on the surface of multilayer body 12 as pre-treatment.

When the plated layer is formed directly on multilayer body 12 withoutproviding underlying electrode layer 32, reduction in thickness bymagnitude of the thickness of underlying electrode layer 32 is able toprovide a lower profile, that is, decrease in thickness, or into athickness of multilayer body 12, that is, a thickness of inner layerportion 18. Therefore, a degree of freedom in design of a thin chip isable to be significantly improved.

The plated layer preferably includes a lower plated electrode formed onthe surface of multilayer body 12 and an upper plated electrode formedon a surface of the lower plated electrode, for example. Each of thelower plated electrode and the upper plated electrode preferablyincludes at least one metal selected, for example, from Cu, Ni, Sn, Pb,Au, Ag, Pd, Bi, and Zn or an alloy including such a metal.

The lower plated electrode preferably includes Ni that provides a solderbarrier and the upper plated electrode preferably includes Sn or Auexcellent in solderability, for example.

For example, when first internal electrode layer 16 a and secondinternal electrode layer 16 b include Ni, the lower plated electrodepreferably includes Cu that is well joined to Ni, for example. The upperplated electrode should only be included as necessary, and each of firstexternal electrode 30 a to fourth external electrode 30 d may be formedonly from the lower plated electrode. The upper plated electrode maydefine and function as and define an outermost layer of the platedlayer, or another plated electrode may further be formed on a surface ofthe upper plated electrode.

When external electrode 30 is formed only from the plated layer withoutunderlying electrode layer 32, one plated layer without includingunderlying electrode layer 32 has a thickness preferably not smallerthan about 1 μm and not larger than about 15 μm, for example.

The plated layer preferably includes no glass, for example. A ratio of ametal per unit volume of the plated layer is preferably not lower thanabout 99 volume %, for example.

A dimension in length direction z of multilayer ceramic capacitor 10including multilayer body 12 and first external electrode 30 a to fourthexternal electrode 30 d is defined as an L dimension, a dimension inheight direction x of multilayer ceramic capacitor 10 includingmultilayer body 12 and first external electrode 30 a to fourth externalelectrode 30 d is defined as a T dimension, and a dimension in widthdirection y of multilayer ceramic capacitor 10 including multilayer body12 and first external electrode 30 a to fourth external electrode 30 dis defined as a W dimension.

Although the dimension of multilayer ceramic capacitor 10 is notparticularly limited, for example, multilayer ceramic capacitor 10 hasthe L dimension in length direction z not smaller than about 1.0 mm andnot larger than about 3.2 mm, the W dimension in width direction y notsmaller than about 0.5 mm and not larger than about 2.5 mm, and the Tdimension in height direction x not smaller than about 0.3 mm and notlarger than about 2.5 mm. The dimension of multilayer ceramic capacitor10 may be measured with a microscope.

In multilayer ceramic capacitor 10 shown in FIG. 1 , the number of firstinternal electrode layers 16 a is larger than the number of secondinternal electrode layers 16 b and at least two first internal electrodelayers 16 a are successively layered. Therefore, multilayer ceramiccapacitor 10 provides improved conduction from first internal electrodelayer 16 a and second internal electrode layer 16 b to externalelectrode 30 while increase in capacitance thereof is reduced orprevented, and thus multilayer ceramic capacitor 10 reduces or preventsan increase in DC resistance.

In multilayer ceramic capacitor 10 shown in FIG. 1 , fifth section 28 band sixth section 28 c of second internal electrode layer 16 b arelarger in thickness than fourth section 28 a of second internalelectrode layer 16 b. Therefore, even when the number of second internalelectrode layers 16 b is reduced in order to lower the capacitance ofmultilayer ceramic capacitor 10, connectivity between second internalelectrode layers 16 b and third external electrode 30 c and connectivitybetween second internal electrode layers 16 b and fourth externalelectrode 30 d is able to be provided.

2. Method of Manufacturing Multilayer Ceramic Capacitor

A method of manufacturing a multilayer ceramic capacitor according to apreferred embodiment of the present invention will now be described.

Initially, a dielectric sheet for a dielectric layer and a conductivepaste for an internal electrode are prepared. The dielectric sheet andthe conductive paste for the internal electrode layer include a binderand a solvent. A known binder or a known solvent may be used.

The conductive paste for the internal electrode layer is printed in aprescribed pattern on the dielectric sheet, for example, by screenprinting or gravure printing. The dielectric sheet having a pattern ofthe first internal electrode layer formed and the dielectric sheethaving a pattern of the second internal electrode layer formed are thusprepared.

More specifically, a screen plate to print the first internal electrodelayer and a screen plate to print the second internal electrode layerare separately prepared, and the pattern of each internal electrodelayer may be printed by a printer that is able to perform separateprinting with the two types of screen plates. A portion to be the fifthsection and the sixth section of the pattern of the second internalelectrode layer is printed as being larger in thickness than a portionto be the fourth section of the pattern of the second internal electrodelayer.

By layering the sheets each having the first internal electrode layerprinted and the sheets each having the second internal electrode layerprinted to provide a desired structure, a portion to be inner layerportion 18 is formed. The sheet having the first internal electrodelayer printed is larger in number than the sheet having the secondinternal electrode layer printed, and at least two sheets having thefirst internal electrode layer printed are successively layered.

Then, a prescribed number of dielectric sheets with no pattern of theinternal electrode layer printed are layered to define a portion to besecond main-surface-side outer layer portion 20 b on the side of thesecond main surface. Thereafter, the portion to be inner layer portion18 formed in the step described above is layered on the portion to besecond main-surface-side outer layer portion 20 b, and a prescribednumber of dielectric sheets having no pattern of the internal electrodelayer printed are layered on the portion to be inner layer portion 18. Aportion to be first main-surface-side outer layer portion 20 a on theside of the first main surface is thus formed. A layered sheet is thusprovided.

In succession, the layered sheet is pressed in a direction of layering,for example, by isostatic pressing, to provide a multilayer block.

Then, the multilayer block is cut in a prescribed size to provide amultilayer chip. A corner and a ridgeline of the multilayer chip may berounded by barrel polishing.

Then, the cut multilayer chip is fired to provide multilayer body 12. Atemperature of firing is preferably not lower than about 900° C. and nothigher than about 1400° C., for example, although it is dependent on amaterial of dielectric layer 14 or internal electrode layer 16.

Underlying Electrode Layer

In succession, third underlying electrode layer 32 c of third externalelectrode 30 c is formed on first side surface 12 c of multilayer body12 provided by firing, and fourth underlying electrode layer 32 d offourth external electrode 30 d is formed on second side surface 12 d ofmultilayer body 12.

In forming the baked layer as underlying electrode layer 32, aconductive paste including a glass component and a metal component isapplied and thereafter baked to define the baked layer as underlyingelectrode layer 32. A temperature of baking at this time is preferablynot lower than about 700° C. and not higher than about 900° C., forexample.

Various methods may be implemented as the method of forming the bakedlayer. For example, a method of extruding a conductive paste through aslit and applying the conductive paste may be applied. In this method,by increasing an amount of the extruded conductive paste, underlyingelectrode layer 32 is able to be formed not only on first side surface12 c and second side surface 12 d but also on a portion of first mainsurface 12 a and a portion of second main surface 12 b.

A roller transfer method is also able be implemented. In the rollertransfer method, in forming underlying electrode layer 32 not only onfirst side surface 12 c and second side surface 12 d but also on aportion of first main surface 12 a and a portion of second main surface12 b, by increasing a pressure in pressing in roller transfer,underlying electrode layer 32 may be formed as far as a portion of firstmain surface 12 a and a portion of second main surface 12 b.

Then, first underlying electrode layer 32 a of first external electrode30 a is formed on first end surface 12 e of multilayer body 12 providedby firing and second underlying electrode layer 32 b of second externalelectrode 30 b is formed on second end surface 12 f of multilayer body12.

In forming the baked layer as underlying electrode layer 32 as informing underlying electrode layer 32 of each of third externalelectrode 30 c and fourth external electrode 30 d, a conductive pasteincluding a glass component and a metal component is applied andthereafter baked to define the baked layer as underlying electrode layer32. A temperature of baking at this time is preferably not lower thanabout 700° C. and not higher than about 900° C., for example.

In a method of forming the baked layer as underlying electrode layer 32of each of first external electrode 30 a and second external electrode30 b, a method of extruding a conductive paste through a slit andapplying the conductive paste or a roller transfer method may beapplied.

In baking, third underlying electrode layer 32 c of third externalelectrode 30 c, fourth underlying electrode layer 32 d of fourthexternal electrode 30 d, first underlying electrode layer 32 a of firstexternal electrode 30 a, and second underlying electrode layer 32 b ofsecond external electrode 30 b may simultaneously be baked, or thirdunderlying electrode layer 32 c of third external electrode 30 c andfourth underlying electrode layer 32 d of fourth external electrode 30 dmay be baked separately from first underlying electrode layer 32 a offirst external electrode 30 a and second underlying electrode layer 32 bof second external electrode 30 b.

Conductive Resin Layer

When underlying electrode layer 32 is formed from a conductive resinlayer, the conductive resin layer is able to be formed by a methodbelow. The conductive resin layer may be formed on a surface of thebaked layer or the conductive resin layer alone may directly be formedon multilayer body 12 without forming the baked layer.

In the method of forming a conductive resin layer, the conductive resinlayer is formed by applying a conductive resin paste including athermosetting resin and a metal component onto the baked layer ormultilayer body 12, subjecting the conductive resin paste to heattreatment at a temperature not lower than about 250° C. and not higherthan about 550° C., for example, and thermally curing the resin. An N2atmosphere is preferably provided as an atmosphere for heat treatment,for example. In order to prevent scattering of the resin and oxidationof various metal components, a concentration of oxygen is preferablyreduced to about 100 ppm or lower, for example.

For example, the method of extruding a conductive resin paste through aslit and applying the conductive resin paste or the roller transfermethod is able to be applied as the method of applying the conductiveresin paste, as in the method of forming underlying electrode layer 32from the baked layer.

Thin Layer

In forming underlying electrode layer 32 from a thin layer, theunderlying electrode layer is able to be formed at a predeterminedlocation where external electrode 30 is to be formed by using masking orthe like, with a thin film formation method, for example, sputtering orvapor deposition. The underlying electrode layer formed from the thinlayer is a layer not larger than about 1 μm that results from depositionof metal particles.

Plated Electrode

A plated electrode may be provided in second section 26 b, third section26 c, fifth section 28 b, and sixth section 28 c where internalelectrode layer 16 of multilayer body 12 is exposed, without providingunderlying electrode layer 32. In this case, the plated electrode isable to be formed by a method below.

First end surface 12 e and second end surface 12 f of multilayer body 12are plated to form lower plated electrodes on second section 26 b andthird section 26 c which are the exposed portions of first internalelectrode layer 16 a, respectively. Similarly, first side surface 12 cand second side surface 12 d of multilayer body 12 are plated to formlower plated electrodes on fifth section 28 b and sixth section 28 cwhich are the exposed portions of second internal electrode layer 16 b,respectively. In plating, any of electrolytic plating and electrolessplating may be used. Electroless plating, however, is disadvantageousdue to its complicated process, because it requires pre-treatment with acatalyst to improve a rate of precipitation of plating. Therefore,electrolytic plating is preferably used, for example. Barrel plating ispreferably used as a plating method, for example. An upper platedelectrode formed on a surface of the lower plated electrode maysimilarly be formed.

In succession, plated layer 34 may be formed on the surface ofunderlying electrode layer 32, the surface of the conductive resin layeror the surface of the lower plated electrode, and the surface of theupper plated electrode.

More specifically, in the present preferred embodiment, an Ni platedlayer is formed as the lower plated layer on underlying electrode layer32 which is the baked layer and an Sn plated layer is formed as theupper plated layer. The Ni plated layer and the Sn plated layer aresuccessively formed, for example, by barrel plating. In plating, any ofelectrolytic plating and electroless plating may be used. Electrolessplating, however, is disadvantageous due to its complicated process,because it requires pre-treatment with a catalyst to improve a rate ofprecipitation of plating. Therefore, electrolytic plating is preferablyapplied, for example.

Multilayer ceramic capacitor 10 according to the present preferredembodiment is manufactured as described above.

3. Experimental Example

In order to check advantageous effects of a multilayer ceramic capacitoraccording to a preferred embodiment of the present invention describedabove, a multilayer ceramic capacitor was manufactured as a sample in anexperiment, and a heat generation characteristic test (variation intemperature with variation in current), a test to measure a DCresistance (Rdc) of the internal electrode layer, and a test to checkconnection between the internal electrode layer and the externalelectrode were conducted.

(1) Specifications of Sample in Example

A multilayer ceramic capacitor according to Example of a preferredembodiment of the present invention with specifications as below wasinitially made in accordance with the method of manufacturing themultilayer ceramic capacitor described above.

EXAMPLE

-   -   Structure of multilayer ceramic capacitor: three-terminal (see        FIG. 1 )    -   Dimension LXWXT of multilayer ceramic capacitor (including a        designed value): about 1.6 mm X about 0.8 mm X about 0.6 mm    -   Material for dielectric layer: BaTiO₃    -   Capacitance: see Example 1 to Example 12 in Table 1    -   Rated voltage: see Example 1 to Example 12 in Table 1    -   Structure of LT cross-section: see FIG. 4 (the second internal        electrode layers dividing the region where at least two first        internal electrode layers were successively layered (internal        electrode layered portion) into a plurality of regions), FIG. 4        showing Example 6    -   Structure of internal electrode        -   First internal electrode layer            -   Material: Ni            -   Shape: see FIG. 6            -   Number of layers: see Example 1 to Example 12 in Table 1            -   Thickness: about 1.0 μm        -   Second internal electrode layer            -   Material: Ni            -   Shape: see FIG. 7 for Example 1 to Example 6 and see                FIG. 8 for Example 7 to Example 12            -   Number of layers: see Example 1 to Example 12 in Table 1            -   Thickness: thickness of fourth section: about 1.0 μm            -   Thickness of fifth and sixth sections: about 1.5 μm    -   Structure of external electrode        -   First external electrode and second external electrode            -   Underlying electrode layer: baked layer including                conductive metal (Cu) and glass component            -   Thickness of end surface in central portion: about 45 μm            -   Plated layer: two-layered structure of Ni plated layer                and Sn plated layer            -   Thickness of Ni plated layer: about 4 μm            -   Thickness of Sn plated layer: about 4 μm        -   Third external electrode and fourth external electrode            -   Underlying electrode layer: baked layer including                conductive metal (Cu) and glass component            -   Thickness of end surface in central portion: about 30 μm            -   Plated layer: two-layered structure of Ni plated layer                and Sn plated layer            -   Thickness of Ni plated layer: about 4 μm            -   Thickness of Sn plated layer: about 4 μm

(2) Specifications of Sample in Comparative Example

In succession, multilayer ceramic capacitors according to ComparativeExample 1 and Comparative Example 2 with specifications as below weremade.

Comparative Example 1

As compared with the multilayer ceramic capacitor according to Example,the multilayer ceramic capacitor according to Comparative Example is athree-terminal multilayer ceramic capacitor identical to the multilayerceramic capacitor in Example except for alternate layering of the firstinternal electrode layers and the second internal electrode layers anddifference in number of internal electrode layers.

FIG. 9 is a cross-sectional view showing a multilayer ceramic capacitor(Comparative Example 1-3) according to Comparative Example 1. Amultilayer ceramic capacitor 1A according to Comparative Example 1includes a multilayer body 2 in a parallelepiped shape, an externalelectrode 3 provided on each of opposing end surfaces, and an externalelectrode 4 provided on each of opposing side surfaces. Multilayer body2 includes a plurality of layered dielectric layers 5 and a plurality offirst internal electrode layers 6 a and a plurality of second internalelectrode layers 6 b layered on dielectric layer 5. First internalelectrode layers 6 a and second internal electrode layers 6 b arealternately layered with dielectric layers 5 being provided betweenfirst internal electrode layers 6 a and second internal electrode layers6 b.

Details of the specifications will be shown below.

-   -   Structure of multilayer ceramic capacitor: three-terminal (see        FIG. 9 )    -   Dimension LXWXT of multilayer ceramic capacitor (including a        designed value): about 1.6 mm X about 0.8 mm X about 0.6 mm    -   Material for dielectric layer: BaTiO₃    -   Capacitance: see Comparative Example 1-1 to Comparative Example        1-12 in Table 2    -   Rated voltage: see Comparative Example 1-1 to Comparative        Example 1-12 in Table 2    -   Structure of LT cross-section: see FIG. 9 (the first internal        electrode layer and the second electrode layer being alternately        layered), FIG. 9 showing Comparative Example 1-3 in Table 2    -   Structure of internal electrode        -   First internal electrode layer            -   Material: Ni            -   Shape: see FIG. 6            -   Number of layers: see Comparative Example 1-1 to                Comparative Example 1-12 in Table 2            -   Thickness: about 1.0 μm        -   Second internal electrode layer            -   Material: Ni            -   Shape: see FIG. 7 for Comparative Example 1-1 to                Comparative Example 1-6 and see FIG. 8 for Comparative                Example 1-7 to Comparative Example 1-12            -   Number of layers: see Comparative Example 1-1 to                Comparative Example 1-12 in Table 2            -   Thickness: thickness of fourth section: about 1.0 μm            -   Thickness of fifth and sixth sections: about 1.0 μm    -   Structure of external electrode        -   First external electrode and second external electrode            -   Underlying electrode layer: baked layer including                conductive metal (Cu) and glass component            -   Thickness of end surface in central portion: about 45 μm            -   Plated layer: two-layered structure of Ni plated layer                and Sn plated layer            -   Thickness of Ni plated layer: about 4 μm            -   Thickness of Sn plated layer: about 4 μm        -   Third external electrode and fourth external electrode            -   Underlying electrode layer: baked layer including                conductive metal (Cu) and glass component            -   Thickness of end surface in central portion: about 30 μm            -   Plated layer: two-layered structure of Ni plated layer                and Sn plated layer            -   Thickness of Ni plated layer: 4 μm            -   Thickness of Sn plated layer: 4 μm

Comparative Example 2

As compared with the multilayer ceramic capacitor according to Example,a multilayer ceramic capacitor according to Comparative Example is athree-terminal multilayer ceramic capacitor identical to the multilayerceramic capacitor in Example except for a thickness identical betweenthe fourth section of the second internal electrode layer and the fifthand sixth sections of the second internal electrode layer.

FIG. 10 is a cross-sectional view showing a multilayer ceramic capacitor(Comparative Example 2-3) according to Comparative Example 2. Amultilayer ceramic capacitor 1B according to Comparative Example 2includes multilayer body 2 in a parallelepiped shape, external electrode3 provided on each of opposing end surfaces, and external electrode 4provided on each of opposing side surfaces. Multilayer body 2 includes aplurality of layered dielectric layers 5 and a plurality of firstinternal electrode layers 6 a and a plurality of second internalelectrode layers 6 b layered on dielectric layers 5. First internalelectrode layers 6 a are larger in number than second internal electrodelayers 6 b and at least two first internal electrode layers 6 a aresuccessively layered. In multilayer ceramic capacitor 1B shown in FIG.10 , second internal electrode layers 6 b divide an internal electrodelayered portion 7 which is a region where at least two first internalelectrodes 6 a are successively layered into a plurality of internalelectrode layered portions 7 a, 7 b, 7 c, . . . , and 7 i.

Details of the specifications will be shown below.

-   -   Structure of multilayer ceramic capacitor: three-terminal (see        FIG. 10 )        -   Dimension L×W×T of multilayer ceramic capacitor (including a            designed value): about 1.6 mm×about 0.8 mm×about 0.6 mm        -   Material for dielectric layer: BaTiO₃        -   Capacitance: see Comparative Example 2-1 to Comparative            Example 2-12 in Table 3        -   Rated voltage: see Comparative Example 2-1 to Comparative            Example 2-12 in Table 3        -   Structure of LT cross-section: see FIG. 10 (the second            internal electrode layers dividing the region (internal            electrode layered portion) where at least two first internal            electrode layers were successively layered into a plurality            of regions), FIG. 10 showing Comparative Example 2-3 in            Table 3    -   Structure of internal electrode        -   First internal electrode layer            -   Material: Ni            -   Shape: see FIG. 6            -   Number of layers: see Comparative Example 2-1 to                Comparative Example 2-12 in Table 3            -   Thickness: about 1.0 μm        -   Second internal electrode layer            -   Material: Ni            -   Shape: see FIG. 7 for Comparative Example 2-1 to                Comparative Example 2-6 and see FIG. 8 for Comparative                Example 2-7 to Comparative Example 2-12            -   Number of layers: see Comparative Example 2-1 to                Comparative Example 2-12 in Table 3            -   Thickness of fourth section: about 1.0 μm            -   Thickness of fifth and sixth sections: about 1.0 μm                Structure of external electrode        -   First external electrode and second external electrode            -   Underlying electrode layer: baked layer including                conductive metal (Cu) and glass component            -   Thickness of end surface in central portion: about 45 μm            -   Plated layer: two-layered structure of Ni plated layer                and Sn plated layer            -   Thickness of Ni plated layer: about 4 μm            -   Thickness of Sn plated layer: about 4 μm        -   Third external electrode and fourth external electrode            -   Underlying electrode layer: baked layer including                conductive metal (Cu) and glass component            -   Thickness of end surface in central portion: about 30 μm            -   Plated layer: two-layered structure of Ni plated layer                and Sn plated layer            -   Thickness of Ni plated layer: about 4 μm            -   Thickness of Sn plated layer: about 4 μm

Tables 1 to 3 show samples in Example, Comparative Example 1, andComparative Example 2 used in the present experimental example.

TABLE 1 The Number of The Number of Rated Capac- Layered First LayeredSecond Voltage itance Internal Electrode Internal Electrode (V) (nF)Layers (Count) Layers (Count) Example 1 16 220 70 25 Example 2 25 100 5920 Example 3 25 47 83 10 Example 4 50 22 65 8 Example 5 50 15 74 6Example 6 50 10 79 4 Example 7 50 4.70 57 10 Example 8 50 2.20 80 5Example 9 50 1.00 86 3 Example 10 50 0.47 65 3 Example 11 50 0.22 70 2Example 12 50 0.10 70 2

TABLE 2 The Number of The Number of Rated Capac- Layered First LayeredSecond Voltage itance Internal Electrode Internal Electrode (V) (nF)Layers (Count) Layers (Count) Comparative 16 220 24 25 Example 1-1Comparative 25 100 19 20 Example 1-2 Comparative 25 47 9 10 Example 1-3Comparative 50 22 7 8 Example 1-4 Comparative 50 15 5 6 Example 1-5Comparative 50 10 3 4 Example 1-6 Comparative 50 4.70 9 10 Example 1-7Comparative 50 2.20 4 5 Example 1-8 Comparative 50 1.00 2 3 Example 1-9Comparative 50 0.47 2 3 Example 1-10 Comparative 50 0.22 1 2 Example1-11 Comparative 50 0.10 1 2 Example 1-12

TABLE 3 The Number of The Number of Rated Capac- Layered First LayeredSecond Voltage itance Internal Electrode Internal Electrode (V) (nF)Layers (Count) Layers (Count) Comparative 16 220 70 25 Example 2-1Comparative 25 100 59 20 Example 2-2 Comparative 25 47 83 10 Example 2-3Comparative 50 22 65 8 Example 2-4 Comparative 50 15 74 6 Example 2-5Comparative 50 10 79 4 Example 2-6 Comparative 50 4.70 57 10 Example 2-7Comparative 50 2.20 80 5 Example 2-8 Comparative 50 1.00 86 3 Example2-9 Comparative 50 0.47 65 3 Example 2-10 Comparative 50 0.22 70 2Example 2-11 Comparative 50 0.10 70 2 Example 2-12

(3) Heat Generation Characteristic Test (Variation in Temperature withVariation in Current)

In samples according to Example and samples according to ComparativeExample 1 and Comparative Example 2, a thermocouple was brought incontact with the surface of the multilayer body of each sample, a DCcurrent was fed between the first external electrode and the secondexternal electrode, and increase in surface temperature of each samplewas measured. Magnitude of the current to each sample was between 0 Aand about 5 A, and variation in temperature of each sample was measuredfor each magnitude of the current.

The samples in the heat generation characteristic test were as follows.In Example, the sample (having the capacitance of about 10 nF andincluding seventy-nine layered first internal electrode layers and fourlayered second internal electrode layers) in Example 6 was provided. InComparative Example 1, the sample (having the capacitance of about 47 nFand including nine layered first internal electrode layers and tenlayered second internal electrode layers) in Comparative Example 1-3 wasprovided. In Comparative Example 2, the sample (having the capacitanceof about 47 nF and including eighty-three layered first internalelectrode layers and ten layered second internal electrode layers) inComparative Example 2-3 was provided. Three samples each were used, andan average value of the samples was calculated. A temperature increasevalue (ΔT) was calculated by subtraction of a surface temperature of themultilayer body—room temperature.

(4) Test for Measuring DC Resistance (Rdc) of Internal Electrode Layer

In the samples according to Example and the samples according toComparative Example 1, a potential difference between the first externalelectrode and the second external electrode was measured while a currentof 100 mA was fed between the first external electrode and the secondexternal electrode, and a value of the potential difference/100 mA wascalculated as the DC resistance (Rdc). As shown in Tables 1 and 2, avalue of the capacitance was different among the samples in Example andComparative Example 1. Twenty samples were prepared for each capacitanceof the samples in Example and Comparative Example 1 and an average valueof the samples was calculated.

(5) Test for Checking Connection Between Internal Electrode Layer andExternal Electrode

Among the samples according to Example and the samples according toComparative Example 2, a sample having the DC resistance equal to orhigher than a prescribed threshold value was determined as defective inconnection, and a ratio of occurrence of defective connection to thetotal number of samples in the whole lot was calculated. As shown inTables 1 and 3, the number of layered second internal electrode layerswas different among the samples in Example and Comparative Example 2. Inorder to set each sample to have a prescribed capacitance, the number oflayered first internal electrode layers was also varied. Ten thousandsamples according to each of Example and Comparative Example 2 wereprepared for each number of layered second internal electrode layers.

Regarding an evaluation result, Table 4 and FIG. 11 show results of theheat generation characteristic test, Tables 5 and 6 and FIG. 12 showresults of the test to measure the DC resistance of the internalelectrode layer, and Tables 7 and 8 and FIG. 13 show results of the testto check connection between the internal electrode layers and theexternal electrode.

TABLE 4 Temperature Increase 

 (° C.) Comparative Comparative Current(A) Example 1-3 Example 2-3Example 6 0 0 0 0 1 3 0.9 0.7 2 9 3.2 2.5 3 19 6.1 5.8 4 32 12.2 11.3 550 18.9 17.6

TABLE 5 Capacitance DC Resistance (nF) (mΩ) Example 1 220 4.5 Example 2100 5.2 Example 3 47 3.5 Example 4 22 4.6 Example 5 15 4.1 Example 6 103.7 Example 7 4.70 5.3 Example 8 2.20 4.1 Example 9 1.00 3.3 Example 100.47 4.5 Example 11 0.22 4.1 Example 12 0.10 4.1

TABLE 6 Capacitance DC Resistance (nF) (mΩ) Comparative Example 1-1 2207.6 Comparative Example 1-2 100 9.8 Comparative Example 1-3 47 20.7Comparative Example 1-4 22 24.8 Comparative Example 1-5 15 34.2Comparative Example 1-6 10 54.0 Comparative Example 1-7 4.70 65.0Comparative Example 1-8 2.20 75.0 Comparative Example 1-9 1.00 96.7Comparative Example 1-10 0.47 122.0 Comparative Example 1-11 0.22 149.4Comparative Example 1-12 0.10 158.1

TABLE 7 The Number of Ratio of Layered Second Defective InternalElectrode Connection Layers (Count) (%) Example 1 25 0.00 Example 2 200.00 Example 3 10 0.00 Example 4 8 0.00 Example 5 6 0.00 Example 6 40.00 Example 7 10 0.00 Example 8 5 0.00 Example 9 3 0.00 Example 10 30.01 Example 11 2 0.01 Example 12 2 0.03

TABLE 8 The Number of Ratio of Layered Second Defective InternalElectrode Connection Layers (Count) (%) Comparative Example 2-1 25 0.00Comparative Example 2-2 20 0.00 Comparative Example 2-3 10 0.01Comparative Example 2-4 8 0.27 Comparative Example 2-5 6 0.11Comparative Example 2-6 4 0.37 Comparative Example 2-7 10 0.05Comparative Example 2-8 5 0.17 Comparative Example 2-9 3 1.29Comparative Example 2-10 3 0.57 Comparative Example 2-11 2 0.63Comparative Example 2-12 2 0.17

(6) Results of Experiment

(a) Results in Heat Generation Characteristic Test

According to Table 4 and FIG. 11 , it was determined that, since thesample of the multilayer ceramic capacitor in each of Example andComparative Example 2 included the internal electrode layered portionwhich was the region where at least two first internal electrode layerswere successively layered, not only a larger number of first internalelectrode layers were provided and a larger number of first internalelectrode layers connected in parallel were provided but also conductionbetween the internal electrode layers and the external electrode wasexcellent, and hence the DC resistance was reduced and accordingly anamount of heat generation was reduced at any current value and increasein temperature could relatively be reduced.

Increase in temperature was slightly less in each sample in Example thanin each sample in Comparative Example 2. This may be because, unlikeeach sample in Comparative Example 2, in each sample in Example, thefifth section and the sixth section of the second internal electrodelayer were larger in thickness than the fourth section of the secondinternal electrode layer, and hence heat in the multilayer ceramiccapacitor conducted to the second internal electrode layer and heat wasreadily radiated from the third external electrode and the fourthexternal electrode.

On the other hand, the sample of the multilayer ceramic capacitor inComparative Example 1 was structured such that the first internalelectrode layers and the second internal electrode layers werealternately layered. Therefore, in the sample as in Comparative Example1-3 including a relatively small number of layered internal electrodelayers of each type and being low in capacitance, not only the number offirst internal electrode layers was small and the number of firstinternal electrode layers connected in parallel was small but alsoconduction between the internal electrode layers and the externalelectrode was lowered and hence the DC resistance was higher. It wasaccordingly determined that the amount of heat generation greatlyincreased with increase in current value and the sample in ComparativeExample 1 was larger in increase in temperature than the samples inExample and Comparative Example 2.

(b) Results of Test for Measuring DC Resistance of Internal ElectrodeLayer

It was determined according to Table 5 and FIG. 12 that, since thesample of the multilayer ceramic capacitor in Example included theinternal electrode layered portion which was the region where at leasttwo first internal electrode layers were successively layered, not onlya larger number of first internal electrode layers were provided and alarger number of first internal electrode layers connected in parallelwere provided but also conduction between the internal electrode layersand the external electrode was excellent and hence the value of the DCresistance in Example 1 to Example 12 was relatively as low as 5.5 mΩ,or lower at any capacitance.

On the other hand, it was determined according to Table 6 and FIG. 12that, since the sample of the multilayer ceramic capacitor inComparative Example 1 was structured such that the first internalelectrode layers and the second internal electrode layers werealternately layered and the number of layered first internal electrodelayers and the number of layered second internal electrode layersdecreased in the order from Comparative Example 1-1 to ComparativeExample 1-6 and from Comparative Example 1-7 to Comparative Example 1-12to lower the capacitance, the value of the DC resistance greatlyincreased.

(c) Results of Test for Checking Connection Between Internal ElectrodeLayer and External Electrode

It was determined according to Table 7 and FIG. 13 that, since the fifthsection of the second internal electrode layer connected to the thirdexternal electrode and the sixth section of the second internalelectrode layer connected to the fourth external electrode were largerin thickness than the fourth section of the second internal electrodelayer in the sample of the multilayer ceramic capacitor in Example,defective connection did not occur in Examples 1 to 9 and substantiallyno defective connection occurred as exemplified as a ratio of defectiveconnection being 0.01% in Example 10 where three second internalelectrode layers were layered, a ratio of defective connection being0.01% in Example 11 where two second internal electrode layers werelayered, and a ratio of defective connection being 0.03% in Example 12where two second internal electrode layers were layered.

On the other hand, it was determined according to Table 8 and FIG. 13that, in the sample of the multilayer ceramic capacitor in ComparativeExample 2, the thickness of the fifth section of the second internalelectrode layer connected to the third external electrode and the sixthsection of the second internal electrode layer connected to the fourthexternal electrode was identical to the thickness of the fourth sectionof the second internal electrode layer which was relatively small, andin particular in Comparative Examples 2-4 to 2-6 and ComparativeExamples 2-8 to 2-12, the number of layered second internal electrodelayers was eight or smaller, and therefore the ratio of defectiveconnection was 0.1% or higher and defective connection between thesecond internal electrode layer and the external electrode was likely.

As set forth above, it was determined that, in the sample of themultilayer ceramic capacitor according to Example, the first internalelectrode layers were larger in number than the second internalelectrode layers and at least two first internal electrode layers weresuccessively layered, and hence not only a larger number of firstinternal electrode layers were provided and a larger number of firstinternal electrode layers connected in parallel were provided whileincrease in capacitance of the multilayer ceramic capacitor wassignificantly reduced or prevented, but also conduction between theinternal electrode layers and the external electrode was significantlyimproved and increase in DC resistance could be significantly reduced orprevented.

It was determined that, in the multilayer ceramic capacitor according tothe preferred embodiments of the present invention, the fifth sectionand the sixth section of the second internal electrode layer were largerin thickness than the fourth section of the second internal electrodelayer, and hence even when the number of the second internal electrodelayers was reduced to lower the capacitance of the multilayer ceramiccapacitor, connectivity between the second internal electrode layer andthe third external electrode and connectivity between the secondinternal electrode layer and the fourth external electrode couldsufficiently be secured.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A multilayer ceramic capacitor comprising: amultilayer body including a plurality of layered dielectric layers, themultilayer body including a first main surface and a second main surfaceopposed to each other in a height direction, a first end surface and asecond end surface opposed to each other in a length directionorthogonal to the height direction, and a first side surface and asecond side surface opposed to each other in a width directionorthogonal to the height direction and the length direction; a pluralityof first internal electrode layers on the plurality of dielectric layersand drawn to the first end surface and the second end surface; aplurality of second internal electrode layers on the plurality ofdielectric layers and drawn to the first side surface and the secondside surface; a first external electrode on the first end surface andconnected to the first internal electrode layers; a second externalelectrode on the second end surface and connected to the first internalelectrode layers; a third external electrode on the first side surfaceand connected to the second internal electrode layers; and a fourthexternal electrode on the second side surface and connected to thesecond internal electrode layers; wherein each of the second internalelectrode layers includes a central section located in a central portionof the dielectric layer and an extending section that extends from thecentral section located in the central portion of the dielectric layerto the first side surface and the second side surface; the firstinternal electrode layers are larger in number than the second internalelectrode layers, at least two of the first internal electrode layersare successively layered, and the extending section is larger inthickness than the central section located in the central portion of thedielectric layer; and a thickness of the extending section of each ofthe second internal electrode layers is larger than a thickness of eachof the first internal electrode layers.
 2. The multilayer ceramiccapacitor according to claim 1, wherein the second internal electrodelayers divide a region where the at least two of the first internalelectrode layers are successively layered into a plurality of regions.3. The multilayer ceramic capacitor according to claim 2, wherein asingle second internal electrode layer divides the region where the atleast two of the first internal electrode layers are successivelylayered into the plurality of regions.
 4. The multilayer ceramiccapacitor according to claim 2, wherein at least two of the secondinternal electrode layers are successively layered to divide the regionwhere the at least two of the first internal electrode layers aresuccessively layered into the plurality of regions.
 5. The multilayerceramic capacitor according to claim 1, wherein at least one of thesecond internal electrode layers is provided between a region where atleast two of the first internal electrode layers located on a side ofthe first main surface are successively layered and the first mainsurface, and at least one of the second internal electrode layers isprovided between a region where at least two of the first internalelectrode layers located on a side of the second main surface aresuccessively layered and the second main surface.
 6. The multilayerceramic capacitor according to claim 1, wherein the second internalelectrode layers are not provided between a region where at least two ofthe first internal electrode layers located on a side of the first mainsurface are successively layered and the first main surface, and thesecond internal electrode layers are not provided between a region whereat least two of the first internal electrode layers located on a side ofthe second main surface are successively layered and the second mainsurface.
 7. The multilayer ceramic capacitor according to claim 1,wherein a dielectric layer adjacent to at least one of the secondinternal electrode layers has a larger thickness than a dielectric layerlying between the first internal electrode layers.
 8. The multilayerceramic capacitor according to claim 1, wherein a relationship of A B issatisfied, where A represents a width of the central section located inthe central portion of the dielectric layer in the length direction thatconnects between the first end surface and the second end surface and Brepresents a width of the extending section in the length direction thatconnects between the first end surface and the second end surface. 9.The multilayer ceramic capacitor according to claim 1, wherein theextending section is exposed at the first side surface and the secondside surface of the multilayer body.
 10. The multilayer ceramiccapacitor according to claim 1, wherein each of the first internalelectrode layers includes a first section located in a central portionof the dielectric layer, a second section that extends from the firstsection to the first end surface, and a third section that extends fromthe first section to the second end surface.
 11. The multilayer ceramiccapacitor according to claim 10, wherein the second section is exposedat the first end surface, and the third section is exposed at the secondend surface.
 12. The multilayer ceramic capacitor according to claim 1,wherein the first internal electrode layers are provided on dielectriclayers that are different from the dielectric layers on which the secondinternal electrode layers are provided.
 13. The multilayer ceramiccapacitor according to claim 1, wherein a ratio of a thickness of thecentral section of the each of the second internal electrode layers to athickness of the extending section of each of the second internalelectrode layers is greater than or equal to about 1.2.
 14. Themultilayer ceramic capacitor according to claim 1, wherein the firstexternal electrode extends from the first end surface of the multilayerbody to cover a portion of each of the first main surface, the secondmain surface, the first side surface, and the second side surface; thesecond external electrode extends from the second end surface of themultilayer body to cover a portion of each of the first main surface,the second main surface, the first side surface, and the second sidesurface; the third external electrode extends from the first sidesurface to cover a portion of each of the first main surface and thesecond main surface, and the fourth external electrode extends from thesecond side surface to cover a portion of each of the first main surfaceand the second main surface.
 15. The multilayer ceramic capacitoraccording to claim 1, wherein each of the first, second, third, andfourth external electrodes includes an underlying electrode layer on themultilayer body and a plated layer that covers the underlying electrodelayer.
 16. The multilayer ceramic capacitor according to claim 15,wherein the underlying electrode layer includes a plurality ofunderlying electrode layers.
 17. The multilayer ceramic capacitoraccording to claim 15, wherein the underlying electrode layer includesat least one of a baked layer, a conductive resin layer, or a thinlayer.
 18. The multilayer ceramic capacitor according to claim 15,wherein the plated layer does not include glass; and a ratio of a metalper unit volume of the plated layer is preferably not lower than about99 volume %.